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// Copyright 2013 Dolphin Emulator Project / 2014 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#pragma once
#include "common/common.h"
#include <fstream>
// defined in Version.cpp
extern const char *scm_rev_git_str;
// On disk format:
//header{
// u32 'DCAC';
// u32 version; // svn_rev
// u16 sizeof(key_type);
// u16 sizeof(value_type);
//}
//key_value_pair{
// u32 value_size;
// key_type key;
// value_type[value_size] value;
//}
template <typename K, typename V>
class LinearDiskCacheReader
{
public:
virtual void Read(const K &key, const V *value, u32 value_size) = 0;
};
// Dead simple unsorted key-value store with append functionality.
// No random read functionality, all reading is done in OpenAndRead.
// Keys and values can contain any characters, including \0.
//
// Suitable for caching generated shader bytecode between executions.
// Not tuned for extreme performance but should be reasonably fast.
// Does not support keys or values larger than 2GB, which should be reasonable.
// Keys must have non-zero length; values can have zero length.
// K and V are some POD type
// K : the key type
// V : value array type
template <typename K, typename V>
class LinearDiskCache
{
public:
// return number of read entries
u32 OpenAndRead(const char *filename, LinearDiskCacheReader<K, V> &reader)
{
using std::ios_base;
// close any currently opened file
Close();
m_num_entries = 0;
// try opening for reading/writing
OpenFStream(m_file, filename, ios_base::in | ios_base::out | ios_base::binary);
m_file.seekg(0, std::ios::end);
std::fstream::pos_type end_pos = m_file.tellg();
m_file.seekg(0, std::ios::beg);
std::fstream::pos_type start_pos = m_file.tellg();
std::streamoff file_size = end_pos - start_pos;
if (m_file.is_open() && ValidateHeader())
{
// good header, read some key/value pairs
K key;
V *value = nullptr;
u32 value_size;
u32 entry_number;
std::fstream::pos_type last_pos = m_file.tellg();
while (Read(&value_size))
{
std::streamoff next_extent = (last_pos - start_pos) + sizeof(value_size) + value_size;
if (next_extent > file_size)
break;
delete[] value;
value = new V[value_size];
// read key/value and pass to reader
if (Read(&key) &&
Read(value, value_size) &&
Read(&entry_number) &&
entry_number == m_num_entries+1)
{
reader.Read(key, value, value_size);
}
else
{
break;
}
m_num_entries++;
last_pos = m_file.tellg();
}
m_file.seekp(last_pos);
m_file.clear();
delete[] value;
return m_num_entries;
}
// failed to open file for reading or bad header
// close and recreate file
Close();
m_file.open(filename, ios_base::out | ios_base::trunc | ios_base::binary);
WriteHeader();
return 0;
}
void Sync()
{
m_file.flush();
}
void Close()
{
if (m_file.is_open())
m_file.close();
// clear any error flags
m_file.clear();
}
// Appends a key-value pair to the store.
void Append(const K &key, const V *value, u32 value_size)
{
// TODO: Should do a check that we don't already have "key"? (I think each caller does that already.)
Write(&value_size);
Write(&key);
Write(value, value_size);
m_num_entries++;
Write(&m_num_entries);
}
private:
void WriteHeader()
{
Write(&m_header);
}
bool ValidateHeader()
{
char file_header[sizeof(Header)];
return (Read(file_header, sizeof(Header))
&& !memcmp((const char*)&m_header, file_header, sizeof(Header)));
}
template <typename D>
bool Write(const D *data, u32 count = 1)
{
return m_file.write((const char*)data, count * sizeof(D)).good();
}
template <typename D>
bool Read(const D *data, u32 count = 1)
{
return m_file.read((char*)data, count * sizeof(D)).good();
}
struct Header
{
Header()
: id(*(u32*)"DCAC")
, key_t_size(sizeof(K))
, value_t_size(sizeof(V))
{
memcpy(ver, scm_rev_git_str, 40);
}
const u32 id;
const u16 key_t_size, value_t_size;
char ver[40];
} m_header;
std::fstream m_file;
u32 m_num_entries;
};
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